- Email: [email protected]
First-in-man phase I study assessing the safety and pharmacokinetics of a 1-hour intravenous infusion of the doxorubicin prodrug DTS-201 every 3 weeks in patients with advanced or metastatic solid tumours
European Journal of Cancer 86 (2017) 240e247
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.ejcancer.com
Original Research
First-in-man phase I study assessing the safety and pharmacokinetics of a 1-hour intravenous infusion of the doxorubicin prodrug DTS-201 every 3 weeks in patients with advanced or metastatic solid tumours Patrick Scho¨ffski a,*, Jean-Pierre Delord b, Etienne Brain c, Jacques Robert d, Herlinde Dumez a, Jamal Gasmi e,1, Andre´ Trouet (t)e a
University Hospitals Leuven, Department of General Medical Oncology, Leuven Cancer Institute, Leuven, Belgium Institut Claudius-Regaud, Universite Paul-Sabatier, Toulouse, France c Institut Curie (Hoˆpital Rene´ Huguenin), Saint Cloud, France d Institut Bergonie´, and Universite´ Victor Segalen Bordeaux 2, Bordeaux, France e Diatos S.A., 166 Boulevard Du Montparnasse, 75014 Paris, France b
Received 1 September 2017; accepted 14 September 2017
KEYWORDS Chemotherapy; Anthracycline; Doxorubicin; Cardiotoxicity; Prodrug
Abstract Purpose: DTS-201 is a doxorubicin (Dox) prodrug that shows encouraging data in experimental models in terms of both efficacy and safety compared with conventional Dox. The purpose of this phase I study was to assess the safety profile, to establish the recommended dose (RD) for clinical phase II studies and to assess potential anticancer activity of the compound. Experimental design: DTS-201 was administered as a 1-hour infusion every 3 weeks in eligible patients with advanced solid tumours according to common clinical phase I criteria. Dose escalation was performed according to a modified Fibonacci schema. Results: Twenty-five patients with a median age of 58 years (range, 30e72) were enrolled in the study. The median number of treatment cycles was 2 (range, 1e8). DTS-201 was administered at four dose levels (DLs) ranging from 80 to 400 mg/m2, which is equivalent to 45e225 mg/m2 of conventional Dox. No dose-limiting toxicity (DLT) occurred at the first two DLs. Three DLTs were observed at DL3 and DL4 (diarrhoea for DL3, vomiting and
* Corresponding author: Department of General Medical Oncology, Leuven Cancer Institute, University Hospitals Leuven, Faculty of Medicine, Department of Oncology, Research Unit Laboratory of Experimental Oncology, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium. Fax: þ32 16 346901. E-mail address: [email protected] (P. Scho¨ffski). 1 Current address: Medpace Inc, 5375 Medpace Way, Cincinnati, OH 45227, United States. https://doi.org/10.1016/j.ejca.2017.09.009 0959-8049/ª 2017 Elsevier Ltd. All rights reserved.
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neutropenia for DL4). DL4 (400 mg/m2 ) was considered the maximum tolerated dose. Myelosuppression was the main toxicity, and NCI-CTC grade IIIeIV neutropenia was common at RD. Non-haematological adverse reactions were mild to moderate and included nausea, anorexia, asthenia and alopecia. No treatment-related severe cardiac adverse events were observed. Conclusions: DTS-201 is well tolerated and safe in heavily pretreated solid tumour patients. A high equivalent dose of Dox could be delivered without severe drug-related cardiac events. DTS-201 showed evidence of clinical activity with a confirmed partial response in a patient with soft-tissue sarcoma. The recommended phase II dose is 400 mg/m2. ª 2017 Elsevier Ltd. All rights reserved.
In the vicinity of a tumour, the tetrapeptide portion of the DTS-201 prodrug is cleaved by endopeptidases that are released extracellularly in the tumour environment. This yields the metabolites N-L-alanyl-L-leucylDox (Ala-Leu-dox) and N-L-leucyl-Dox (Leu-dox), which can enter cells and are then converted to the active drug Dox. This results in an increased concentration of Dox in the tumour cells and reduced Dox levels in normal tissues [4]. Two tumour-specific endopeptidases have been identified, which cleave DTS-201: neprilysin (CD10, EC3.4.24.11) and thimet oligopeptidase (TOP, EC3.4.24.15). These endopeptidases are released in the extracellular space of solid tumours by stromal, tumour and neoangiogenic endothelial cells or expressed on their cell surface. The extracellular localisation of these enzymes permits to cleave and activate DTS-201 [4e8]. A significant therapeutic advantage of DTS-201 as an endopeptidase activated prodrug compared with free Dox has been demonstrated in a number of different tumour models including breast, colon, prostate and lung cancers. Pharmacokinetic and tissue distribution studies in normal and tumour-bearing mice have confirmed that an improved therapeutic index of the prodrug results in a tumour-selective release of Dox and a significant decrease in Dox levels in all normal tissues.
1. Introduction Doxorubicin (Dox) is among the most widely used cytotoxic agents for the treatment of various types of cancer, but the clinical benefit brought by this agent is limited due to its toxicity profile, which includes not only reversible acute adverse events such as myelosuppression, nausea, vomiting and alopecia but also irreversible cumulative cardiac damage [1]. Secondgeneration anthracyclines such as epirubicin showed some safety improvement, but the risk of inducing cardiomyopathy remains high [2]. During the last few decades, to improve the therapeutic index, a tremendous effort has been done to develop safer anthracyclines, focussing on analogues and tumour-targeted formulations [3]. DTS-201 (or CPI-0004Na), N-succinyl-b-alanyl-Lleucyl-L-alanyl-L-leucyl-Dox, is a peptidic prodrug of Dox that remains stable and inactive in its cellimpermeable prodrug form (Fig. 1). The drug has been developed by the late Trouet et al. [4]. In 2003, Diatos S.A. licensed from Medarex certain European rights to develop and commercialise DTS-201. Later Medarex (now a subsidiary of Bristol-Myers Squibb) granted full European commercialisation rights for DTS-201 to Diatos S.A.
O
OH
O
OH
O
HO HO
O
Na+
H N
O
H N
O N H
O
O
H N
O
O
O
N H
O
HO
Hemisuccinate N-masking group
β-Ala
Leu
Ala
Leu
Fig. 1. Chemical structure of DTS-201.
Doxorubicin
O
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Subsequent toxicology studies in rats showed that the chronic treatment with DTS-201 was less cardiotoxic when compared with free Dox at doses up to eight-fold higher. Increased tumour exposure with reduced cardiac exposure to Dox in animals after treatment with DTS201 provides a strong rationale for this prodrug approach [9]. Based on these interesting preclinical findings, DTS201 was selected as an investigational product for clinical development. The purpose of this first-in-man study was to assess the maximum tolerated dose (MTD), to characterise the safety profile, to determine the pharmacokinetic profile, to determine the phase II recommended dose (RD) and to assess the preliminary antitumour activity of DTS-201.
2. Materials and methods This phase I trial included adult patients with solid tumours whose disease had progressed on standard therapy, with a World Health Organisation performance status of 0 or 1, who had received a maximum of three lines of chemotherapy for locally advanced or metastatic disease, with absolute neutrophil and platelet counts 1500/mL and 100,000/mL respectively, normal serum albumin and creatinine, AST/ALT and alkaline phosphatase <2.5 of the upper limit of normal. Patients had normal cardiac function and a normal left ventricular ejection fraction (LVEF) at study entry. Exclusion criteria included prior anthracycline exposure of more than 300 mg/m2 of cumulative total equivalent of Dox or a failure of previous anthracycline-based chemotherapy within 6 months after adjuvant therapy or 3 months after discontinuation of treatment in the metastatic setting, serious concomitant illness, prior radiation therapy or systemic anticancer therapy within 4 weeks (6 weeks for mitomycin C and nitrosoureas), symptomatic brain metastasis and prior radiation therapy to more than 30% of the bone marrow. All patients gave written informed consent. This study had the approval of all responsible national and local ethics committees. The baseline evaluation was performed within 1 week before the study enrolment. Interim evaluation at each treatment cycle included physical examination, vital signs, electrocardiogram (ECG), concomitant medications and laboratory investigations. The tumour response evaluation was done every two cycles according to the Response Evaluation Criteria in Solid Tumours (RECIST) [10]. Laboratory investigations were done on days 8 and 15 of every treatment cycle. Cardiac monitoring was performed for every cycle using an ECG and serum troponin evaluations and through echocardiography for every other treatment cycle. Adverse events were monitored continuously throughout the study period and graded according to
the NCI-CTC criteria (version 3). For the determination of plasma levels of DTS-201 and analytes, blood samples were collected up to 72 h after the first administration of DTS-201. 2.1. Drug administration DTS-201 was supplied as a sterile red-orange lyophilised prodrug manufactured in compliance with Good Manufacturing Practice. It was supplied in 10-ml vials containing 100 mg of DTS-201 and 100 mg of lactose monohydrate. DTS-201 was reconstituted by adding sterile 5% D-glucose and administered as a 1-hour infusion. All doses of DTS-201 mentioned in this study report describe the Dox-equivalent dose. Standard prophylactic systemic anti-emetic treatment was allowed according to the protocol of each institution. 2.2. Study design The aim of this non-randomised, open-label, doseescalating, multicentre trial was to assess the MTD of DTS-201 administered as a 1-hour intravenous infusion every 3 weeks. Assessing safety, determining the RD and investigating clinical efficacy were the main secondary end-points. The dose escalation scheme was based on a modified Fibonacci schedule. Three patients entered at each dose level (DL), which could be extended to a maximum of 6 in case of dose-limiting toxicity (DLT). If two DLTs were observed at a given DL, the dose was declared the MTD, and no further dose escalation occurred. The MTD was determined according to the DLTs occurring during the first treatment cycle (3 weeks). The phase II RD was defined to be either the MTD or an intermediate DL between the MTD and the DL below. Patients continued treatment until disease progression or the occurrence of unacceptable toxicity or until at least six treatment cycles were completed. Treatment beyond six treatment cycles had to be discussed between the investigator and the sponsor on a case-by-case basis [11]. 2.3. Blood sampling and pharmacokinetic analysis According to protocol, 14 blood samples were drawn from all patients during the first cycle; at pre-dosing and then after the DTS-201 administration, at 15 and 30 min, 1, 1.5, 2, 3, 4, 6, 8, 24, 48 and 72 h. At each time point, 4 ml of venous blood was collected in polypropylene tubes containing citrate. The blood sample was then placed on ice and centrifuged for 10 min at 4 C. The plasma was transferred into two appropriate polypropylene tubes and was immediately frozen at 20 C. The pharmacokinetic analysis of the plasma levels of DTS-201 and its metabolites (AL-Dox, L-Dox, Dox and doxorubicinol) was performed for each patient
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at each DL using the trapezoidal method, the log-linear model (regression and the optimisation method).
3. Results Between July 2005 and June 2007, a total of 25 patients were enrolled into the study in three sites (one in Belgium and two in France). Thirteen patients were female and 12 were male. The mean age was 57.4 years (range, 30e71). Six patients had lung cancer and five had prostate cancer. Breast cancer, pancreatic cancer and head and neck cancer were the primary tumour for three patients each, two patients had soft-tissue sarcoma, the other patients had gastric, renal and oesophageal cancer. Patient characteristics are presented in Table 1. All patients were eligible for the trial. A total of 23 patients (92%) had visceral disease involvement. The mean number of disease sites was three per patient. The majority of patients had received surgery (68%), prior radiation therapy (72%) and prior chemotherapy (96%). Fourteen patients had received two prior lines of chemotherapy and six patients had received previous anthracycline treatment.
243
201 administered reached 2750 mg/m2 in individual patients. The dose escalation schema is shown in Table 2. No DLTs were observed during the DLT window at the DLs of 80 and 160 mg/m2. DLTs occurred in one patient at the 250 mg/m2 DL (grade III mucositis) and in two patients in the 400 mg/m2 cohort (grade IV neutropenia lasting more than 5 days and grade III vomiting). The DLTs observed at this DL defined 400 mg/m2 every 3 weeks as the MTD and the phase II RD. To gain further insight into the safety and pharmacokinetics with this DL, six additional patients were treated at this dose, expanding the patient number to 12. One of the six additional patients developed a DLT (febrile neutropenia). 3.2. Deaths Four patients died within 30 days after study discontinuation, three due to disease progression (one at 160 mg/m2 and two at the 400 mg/m2 DL) after two cycles of treatment; the 4th patient died at the 160 mg/ m2 DL without signs of progression. There was no DTS201-related death.
3.1. MTD
3.3. Haematological toxicity
A total of 86 cycles of DTS-201 were administered to 25 patients (median two per patient; range, 1e8). Five cycles were given at the DL 80 mg/m2, 10 cycles at 160 mg/ m2, 24 cycles at 250 mg/m2 and 44 cycles at the 400 mg/ m2 DL. The maximum cumulative total dose of DTS-
Haematological toxicity was evaluated weekly with a complete blood count. Grade III or IV haematological toxicity was observed at the 400 mg/m2 DL, including neutropenia occurring in 11 of the 14 patients (91.7%). Grade III anaemia and thrombocytopenia occurred in five and one patient, respectively (Table 3). The median time to nadir of grade III or IV neutropenia was 15 days, with a relatively short median duration of 5 days.
Table 1 Patient characteristics. Characteristics
n (%)
Total number Age, years Median Range Gender Male Female Primary diagnosis Prostate cancer Breast cancer Pleural mesothelioma Pancreatic adenocarcinoma Non-small cell lung carcinoma Other Number of lines of prior chemotherapy 0 1 2 3 Prior radiotherapy Yes No Prior administration of anthracyclines
25 (100)
Table 2 Treatment dose levels.
59 30e71 13 (52) 12 (48) 5 3 3 3 2 9
(20) (12) (12) (12) (8) (36)
1 (4) 9 (37.5) 14 (58.3) 1 (4) 18 (72) 7 (28) 6 (24)
Treatment dose levels Dose level
DTS-201, mg/m2
DTS-201, mg doxorubicin equivalent/m2
Number of patients
DL1 DL2 DL3 DL4
80 160 250 400
45 90 140 225
3 3 7 12
Table 3 Haematological toxicity (number of patients by dose-level cohort). NCI-CTC grade IIIeIV
80 mg/m2 160 mg/m2 250 mg/m2 400 mg/m2 (3) (3) (7) (12)
Leukopenia Neutropenia Anaemia Thrombocytopenia Febrile neutropenia
0 0 0 0 1 (33.3%) 1 (33.3%) 0 0 0 0
0 0 0 0 0
10 (83.3%) 11 (91.7%) 3 (25%) 1 (8.3) 3 (25%)
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Neutropenia was complicated by fever in three patients and was observed at the MTD. A treatment delay for toxicity was necessary in only two patients, one for grade IV neutropenia after the first cycle and the second for grade III mucositis after the third course. Both were noticed at the 400 mg/m2 DL and led to a treatment delay of only 1 week. 3.4. Non-haematological toxicity All patients experienced at least one non-haematological adverse event. Table 4 summarises the drug-related adverse events. The number of patients with DTS-201related adverse events increased with increasing dose; however, the majority of side-effects were of mild to moderate intensity. The most commonly reported events were nausea, vomiting, fatigue and alopecia. No grade IV non-haematological toxicity occurred during the study. Grade III diarrhoea was observed in one patient at the 250 mg/m2 DL; another patient who received 250 mg/m2 of DTS-201 and who had a head and neck cancer previously treated with radiation therapy, developed grade III mucositis, which was interpreted as a recall radiation effect. This patient was replaced. Grade III nausea, vomiting, mucositis and asthenia were reported for one patient each in the 400 mg/m2 cohort. 3.5. Cardiac toxicity The majority of patients had normal ECG evaluations throughout the study. Three patients at the 400 mg/m2 dose had clinically asymptomatic ECG changes. One patient showed no significant abnormality during the treatment courses but a non-specific ST and T wave abnormality after six cycles of DTS-201. Another patient with cardiovascular risk factors (hypertension, hypercholesterolaemia and obesity) had an incidental increase of troponin after the sixth cycle, which was rapidly reversible and was considered as possibly drug related. No clinical cardiac symptoms have been reported for this patient; however, after the 7th cycle of DTS-201, the ECG showed a significant abnormality suggestive of myocardial ischaemia, but LVEF values remained unchanged during the whole study period. One patient had ECG findings consistent with myocardial infarction at study entry, but during the study, this Table 4 Grade III/IV non-haematological toxicity (number of patients by doselevel cohort). NCI-CTC grade III
80 mg/m2 (3)
160 mg/m2 (3)
250 mg/m2 (7)
400 mg/m2 (12)
Nausea Vomiting Mucositis Asthenia Diarrhoea
0 0 0 0 0
0 0 0 0 0
0 0 0 0 1 (14.3%)
1 1 2 1 0
(8.3%) (8.3%) (16.7%) (8.3%)
patient did not have any change in LVEF or ECG changes. LVEF values were comparable between dosing cohorts. No drop in LVEF was observed during the study period for the total patient population. 3.6. Tumour response Efficacy of DTS-201 was not the primary end-point for this phase I study, but 22 patients who received at least two cycles of treatment were evaluable for response according to RECIST. No partial or complete responses were observed at the 80, 160 and 250 mg/m2 DLs. In the 400 mg/m2 cohort, one patient with lung metastases from soft-tissue sarcoma, previously untreated with chemotherapy, achieved a confirmed partial response. In addition, 12 patients at different DLs achieved stable disease as the best RECIST response. 3.7. Pharmacokinetics and pharmacodynamics Fourteen blood samples were collected per patient at cycle 1, from the initiation of infusion and up to 72 h post dose. Pharmacokinetic analysis demonstrated that DTS-201 is metabolised to AL-Dox, L-Dox and then to Dox and doxorubicinol. DTS-201 concentration peaked at the end of the 1-hour infusion and then declined rapidly. The metabolites followed distinct patterns: ALDox was barely detectable in most samples; L-Dox followed a time course parallel to that of DTS-201 with a Cmax also reached at the end of the infusion; Dox and doxorubicinol appeared later (Tmax of 1.25 and 4 h, respectively) and were present in plasma for longer periods than DTS-201. The plasma concentration versus time curves of DTS-201 and its metabolites generated with the results obtained from the 12 patients treated at 400 mg/m2 are presented in Fig. 2. Area under the curve (AUC) values of DTS-201 and its metabolites are presented in Table 5. For the parent drug as for metabolites, the AUC0-T was linearly correlated with the dose. L-Dox, Dox and doxorubicinol had AUC values 4- to 12-fold lower than those of DTS-201. AL-Dox seemed to be a minor metabolite with AUC values 250- to 1000fold lower than those of DTS-201. The proportions of the various metabolites were independent of the administered dose of DTS-201. The main pharmacokinetic parameters of DTS-201 (total plasma clearance, elimination half-life and total volume of distribution at steady state) were also independent of the DL administered. Of note, plasma AUCs of Dox after administration of 400 mg/m2 DTS-201 were similar to those obtained after administration of a dose of 50e60 mg/m2 of conventional Dox, whereas Cmax values were much lower, and the doxorubicinol/Dox ratio was higher. These features are important when considering the dose equivalence for haematologic and cardiac toxicity. We also observed a significant relationship between
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Pla sm a co ncentratio n (ng/m L
100000
A
10000 1000 100 10 1 0
Pla sm a co ncentra tion (ng /m L
10000
2
B
4 Time (hours) 1000
6
8
C
1000 100 100 10 10
1
1 0
2
4 Time (hours)
6
8
0
20
40 Time (hours)
60
80
Fig. 2. Plasma concentration versus time curves of DTS-201 and its metabolites. Data collected from 12 patients treated at the dose 400 mg/m2. Values are mean SD. DTS-201 (- -), AL-Dox (ο), L-Dox ( × ), doxorubicin (- -), doxorubicinol (◊). (A) DTS-201 concentration evolution. (B) Metabolites pharmacokinetics profile up to 8 h post dose. (C) Doxorubicin and doxorubicinol concentration up to 72 h post dose.
leucocyte counts and Dox AUC (and not the prodrug AUC). Table 6 summarises the key pharmacokinetic parameters of DTS-201. 4. Discussion Conventional anthracyclines are widely used cytotoxic agents for the treatment of multiple types of cancer; however, the clinical benefit with these agents is limited due to their safety profile, in particular the well-known cardiotoxicity. The overall risk of conventional anthracycline-induced cardiotoxicity is related to the cumulative administered dose of the agents. Conventional Dox-induced congestive heart failure may occur at cumulative doses lower than the currently accepted lifetime cumulative dose of 450e500 mg/m2, especially in older patients. The incidence of heart failure was Table 5 AUC values (ng/ml h) of DTS-201 and its metabolites. Number of patients at each dose level indicated between parentheses. Results are given as mean values (SD for the 400 mg/m2 data). 80 mg/m2 (3) 160 mg/m2 (3) 250 mg/m2 (7) 400 mg/m2 (12) DTS-201 AL-Dox L-Dox Dox Dox-ol
1364 3.33 125 101 222
4476 4.26 577 390 867
6118 20.9 1027 853 1308
11,062 4459 29.3 11.4 1389 385 1418 378 2348 1030
reported to be 2%, 8% and 26% of patients at total cumulative doses of 300 mg/m2, 450 mg/m2 and 550 mg/ m2, respectively [12]. During the last 30 years, research has focussed to develop more-effective and less-toxic anthracyclines. The initial attempt concentrated on analogues of Dox and daunorubicin, without achieving a significant improvement in the therapeutic index. Other alternatives included the use of long infusion schedules, Table 6 Pharmacokinetic parameters of DTS-201. 80 mg/m2 160 mg/m2 250 mg/m2 400 mg/m2 (1) (3) (7) (12) Total plasma clearance (L/h) Elimination half-life (h) Volume of distribution (L) Mean residence time (h)
71.3
65.9
90.8
86.0 31.0
0.112
0.303
0.425
0.385 0.347
11.5
12.0
19.5
27.4 12.2
0.161
0.198
0.234
0.322 0.116
The pharmacokinetic parameters of DTS-201 were estimated with the APIS software, using a model at 1 or 2 compartments, chosen according to the Akaike criterion. The parameters were independent from the dose administered. The data best fitted a one-compartment model for 15 patients and a two-compartment model for 8 patients. In two cases, at the dose of 80 mg/m2, no modelling was possible. The use of two or three compartments did not impact on total plasma clearance, volume of distribution at steady state or mean residence time but impacted on the half-life, the use of two compartments giving rise to apparently longer elimination half-lives.
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of iron-chelating agent dexrazoxane and ACEinhibitors, and the development of tumour-targeted formulations, including liposomal or albumin-bound anthracyclines or the conjugation of anthracyclines to a carrier that specifically recognises tumour cells. DTS201 is a Dox prodrug that is unable to enter normal cells but is activated by peptidases secreted by cancer cells. In preclinical models, DTS-201 was found to be more effective and less cardiotoxic than free Dox. In the present study, we have shown that DTS-201 can be administered safely at doses of Dox higher than those usually prescribed. To reach the MTD, the Doxequivalent dose can be increased by a factor of 3: 400 mg/m2 of DTS-201 corresponds to 225 mg/m2 of free Dox, which is three times higher than the standard 75 mg/m2 of conventional Dox used as a single agent in many diseases. At this high DL, the acute toxicity profile of DTS-201 was similar to that of Dox, including myelosuppression, mucositis, nausea, vomiting and alopecia in the absence of cardiac toxicity. Interestingly, the neutropenic episodes in this study were of very short duration and fully reversible. Five patients in the MTD cohort received a total of six cycles of therapy, reaching a total cumulative dose of 2750 mg/m2, which corresponds to a dose of 1546 mg/m2 of free Dox. This cumulative dose of Dox is about threefold higher than the generally recommended cumulative lifetime dose of the conventional cytotoxic agent. Cardiac safety was closely monitored throughout our study. All patients had longitudinal ECG, plasma troponin and cardiac ultrasound assessments. No significant drop in LVEF was noticed. One patient with a history of cardiovascular risk factors had an incidental increase of troponin after the sixth cycle. This was rapidly reversible, not complicated by clinical cardiac findings but was considered as possibly drug related. Of note, incidental increases in serum troponin are not an uncommon finding in patients with advanced solid tumours. Plasma concentrations of DTS-201 increased linearly with increasing dose. The pharmacokinetic profile of DTS-201 is characterised by a relatively short half-life and a small volume of distribution, indicating that DTS201 remains in the plasma compartment and is progressively converted into AL-Dox and L-Dox and then to Dox by further enzymatic cleavage. The Dox AUC after treatment with DTS-201 at 400 mg/m2 is within the range of AUC values reported for 50e60 mg/m2 of free Dox [13e16]. Despite that the objectives of this study were to determine the MTD and the phase II RD, 59% of the patients entering this trial had clinical benefit: one patient had a confirmed partial response and 12 patients achieved disease stabilisation. Disease control was observed in different tumour types. On the basis of the phase I trial presented here, Diatos S.A. started two phase II trials, one in advanced prostate adenocarcinoma and one in metastatic breast cancer.
In summary, this first-in-man study validated the concept that an extracellularly tumour-activated anthracycline prodrug can be used safely in patients with advanced malignancies and that the administration of such agent is associated with an improved therapeutic window. The toxicity profile after administration of higher doses of DTS-201 appeared less severe than that observed with the administration of standard doses of free Dox. During dose escalation, patients could be safely exposed to repeated cycles of DTS-201 with doses up to three-fold higher than the recommended cumulative lifetime maximum dose of conventional Dox. Moreover, no severe acute cardiac toxicity was observed in this trial. Some signs of tumour activity in various tumour types were seen, which is encouraging but needs to be confirmed in clinical phase II studies. Future studies will also have to assess long-term safety of this tumour-activated anthracycline prodrug, as cardiac toxicity due to conventional Dox can also occur after longer treatment-free intervals. In addition, the role of the endopeptidases as potential predictive biomarkers for the antitumour effects of the prodrug should be assessed. We also hypothesise that this agent might be active in solid tumours beyond the traditional Dox-sensitive entities, due to a specific high activity of peptidases found in some cancers. These enzymes would then be responsible for an indirect ‘vectorisation’ or delivery of very high concentrations of the active compound in the vicinity of tumour cells. Partly sparing the cardiac exposure to toxic metabolites, we also believe that this drug could allow both prolonged and repeated anthracycline exposure of patients with Dox-sensitive tumours. This is supported by DTS-201 cardiac safety profile as observed in this phase I study. Further development of DTS-201 should focus on patients with and without prior anthracycline exposure. Patients could potentially be selected for such treatment by the presence or absence of the endopeptidases required for cleavage of the agent. Based on the safety profile of the drug, DTS-201 would also qualify as a combination partner with other cardiotoxic or noncardiotoxic anticancer agents [17]. The working hypothesis behind the development of DTS-201 has been developed further in sarcoma. A DTS-201-related endopeptidase-activated prodrug, ALGP-Dox, has recently been tested in patient-derived xenograft sarcoma models. ALGP-Dox caused tumour volume stabilisation in de-differentiated liposarcoma xenografts and significant tumour shrinkage in synovial sarcoma, continuing after treatment cessation. A significant decrease in proliferation and an increase in apoptosis compared with control and Dox was observed during and after treatment in all tested models. ALGPDox showed higher antitumoural efficacy compared with Dox and the administration of a 30- to 40-fold higher dose of ALGP-Dox was tolerated without significant adverse events [18].
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In the clinic there remains a high need for further optimisation of anthracycline treatment, both in solid tumours and in haematological malignancies, illustrated by the presentation of randomised phase III data exploring the albumin-bound drug aldoxorubicin in patients with advanced soft-tissue sarcoma, but also by the very recent approval of a liposome-encapsulated combination of daunorubicin and cytarabine for the treatment of adults with newly diagnosed, therapyrelated acute myeloid leukaemia or leukaemia with myelodysplasia-related changes [19,20].
[6]
[7]
[8]
[9]
Conflict of interest statement [10]
Jamal Gasmi is a former employee of Diatos S.A. and approved the submission of this manuscript. The remaining authors declare no conflicts of interest. [11]
Acknowledgements [12]
The authors want to dedicate this article to the late Prof. Andre´ Trouet, who developed DTS-201 and related compounds but passed away on 03-04-2014. We also want to thank Denis Ravel, Florence Gonzalez, Maria Quedraogo, Vincent Dubois, John Tche´linge´rian, Elise Assouly, Karine Vialatte and Matthieu Michel for their support and suggestions during the study. We also thank Azzeddine Cherfi for his advice regarding biometrics.
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novel peptide prodrugs for the therapy of CD10þ tumors. Cancer Res 2003;63:5526e31. Dubois V, Nieder M, Collet F, et al. Thimet oligopeptidase (EC 3.4.24.15) activates CPI-0004Na, an extra-cellularly tumor-activated prodrug of doxorubicin. Eur J Cancer 2006;42:3049e56. Ferro ES, Tambourgi DV, Gobersztejn F, et al. Secretion of a neuropeptide-metabolizing enzyme similar to endopeptidase 22.19 by glioma C6 cells. Biochem Biophys Res Commun 1993;191: 275e81. Crack PJ, Wu TJ, Cummins PM, et al. The association of metalloendopeptidase EC 3.4.24.15 at the extra-cellular surface of the AtT-20 cell plasma membrane. Brain Res 1999;835:113e24. Ravel D, Dubois V, Quinonero J, et al. Preclinical toxicity, toxicokinetics, and antitumor efficacy studies of DTS-201, a tumorselective peptidic prodrug of doxorubicin. Clin Cancer Res 2008;14:1258e65. Therasse P, Arbuck SG, Eisenhauer EA, et al. New guidelines to evaluate the response to treatment in solid tumors. European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada. J Natl Cancer Inst 2000;92:205e16. Storer BE. Design and analysis of phase I clinical trials. Biometrics 1989;45:925e37. Swain SM, Whaley FS, Ewer MS. Congestive heart failure in patients treated with doxorubicin: a retrospective analysis of three trials. Cancer 2003;97:2869e79. Benjamin RS, Riggs CE, Bachur NR. Plasma pharmacokinetics of adriamycin and its metabolites in human with normal hepatic and renal function. Cancer Res 1977;37:1416e20. Brenner DE, Grosh WW, Noone R. Human plasma pharmacokinetics of doxorubicin: comparison of bolus and infusional administrations. Cancer Trea Symp 1984;3:77e83. Eksborg S, Stendahl H, Lonroth U. Comparative pharmacokinetic study of adriamycin and 40 -epiadriamycin after their simultaneous intravenous administration. Eur J Clin Pharmacol 1986;30:629e31. Speth PA, Van Hoesel QG, Haanen C. Clinical pharmacokinetics of doxorubicin. Clin Pharmacokinet 1988;15:15e31. Rayson D, Richel D, Chia S, et al. Anthracycline-trastuzumab regimens for HER2/Neu-overexpressing breast cancer: current experience and future strategies. Ann Oncol 2008;19: 1530e2153. Cornillie J, Wozniak A, Pokreisz P, et al. In vivo antitumoral efficacy of PhAc-ALGP-doxorubicin, an enzyme-activated doxorubicin prodrug, in patient-derived soft tissue sarcoma xenograft models. Mol Cancer Ther 2017 May 31. https://doi.org/10.1158/ 1535-7163.MCT-16-0832. pii: molcanther.0832.2016, [Epub ahead of print]. Chawla S. Phase III study of aldoxorubicin vs investigators’ choice as treatment for relapsed/refractory soft tissue sarcomas. In: Oral Abstract Session: Sarcoma, ASCO Annual Meeting; 2017. https://www.fda.gov/Drugs/InformationOnDrugs/ ApprovedDrugs/ucm569950.htm.
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Original Research
First-in-man phase I study assessing the safety and pharmacokinetics of a 1-hour intravenous infusion of the doxorubicin prodrug DTS-201 every 3 weeks in patients with advanced or metastatic solid tumours Patrick Scho¨ffski a,*, Jean-Pierre Delord b, Etienne Brain c, Jacques Robert d, Herlinde Dumez a, Jamal Gasmi e,1, Andre´ Trouet (t)e a
University Hospitals Leuven, Department of General Medical Oncology, Leuven Cancer Institute, Leuven, Belgium Institut Claudius-Regaud, Universite Paul-Sabatier, Toulouse, France c Institut Curie (Hoˆpital Rene´ Huguenin), Saint Cloud, France d Institut Bergonie´, and Universite´ Victor Segalen Bordeaux 2, Bordeaux, France e Diatos S.A., 166 Boulevard Du Montparnasse, 75014 Paris, France b
Received 1 September 2017; accepted 14 September 2017
KEYWORDS Chemotherapy; Anthracycline; Doxorubicin; Cardiotoxicity; Prodrug
Abstract Purpose: DTS-201 is a doxorubicin (Dox) prodrug that shows encouraging data in experimental models in terms of both efficacy and safety compared with conventional Dox. The purpose of this phase I study was to assess the safety profile, to establish the recommended dose (RD) for clinical phase II studies and to assess potential anticancer activity of the compound. Experimental design: DTS-201 was administered as a 1-hour infusion every 3 weeks in eligible patients with advanced solid tumours according to common clinical phase I criteria. Dose escalation was performed according to a modified Fibonacci schema. Results: Twenty-five patients with a median age of 58 years (range, 30e72) were enrolled in the study. The median number of treatment cycles was 2 (range, 1e8). DTS-201 was administered at four dose levels (DLs) ranging from 80 to 400 mg/m2, which is equivalent to 45e225 mg/m2 of conventional Dox. No dose-limiting toxicity (DLT) occurred at the first two DLs. Three DLTs were observed at DL3 and DL4 (diarrhoea for DL3, vomiting and
* Corresponding author: Department of General Medical Oncology, Leuven Cancer Institute, University Hospitals Leuven, Faculty of Medicine, Department of Oncology, Research Unit Laboratory of Experimental Oncology, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium. Fax: þ32 16 346901. E-mail address: [email protected] (P. Scho¨ffski). 1 Current address: Medpace Inc, 5375 Medpace Way, Cincinnati, OH 45227, United States. https://doi.org/10.1016/j.ejca.2017.09.009 0959-8049/ª 2017 Elsevier Ltd. All rights reserved.
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neutropenia for DL4). DL4 (400 mg/m2 ) was considered the maximum tolerated dose. Myelosuppression was the main toxicity, and NCI-CTC grade IIIeIV neutropenia was common at RD. Non-haematological adverse reactions were mild to moderate and included nausea, anorexia, asthenia and alopecia. No treatment-related severe cardiac adverse events were observed. Conclusions: DTS-201 is well tolerated and safe in heavily pretreated solid tumour patients. A high equivalent dose of Dox could be delivered without severe drug-related cardiac events. DTS-201 showed evidence of clinical activity with a confirmed partial response in a patient with soft-tissue sarcoma. The recommended phase II dose is 400 mg/m2. ª 2017 Elsevier Ltd. All rights reserved.
In the vicinity of a tumour, the tetrapeptide portion of the DTS-201 prodrug is cleaved by endopeptidases that are released extracellularly in the tumour environment. This yields the metabolites N-L-alanyl-L-leucylDox (Ala-Leu-dox) and N-L-leucyl-Dox (Leu-dox), which can enter cells and are then converted to the active drug Dox. This results in an increased concentration of Dox in the tumour cells and reduced Dox levels in normal tissues [4]. Two tumour-specific endopeptidases have been identified, which cleave DTS-201: neprilysin (CD10, EC3.4.24.11) and thimet oligopeptidase (TOP, EC3.4.24.15). These endopeptidases are released in the extracellular space of solid tumours by stromal, tumour and neoangiogenic endothelial cells or expressed on their cell surface. The extracellular localisation of these enzymes permits to cleave and activate DTS-201 [4e8]. A significant therapeutic advantage of DTS-201 as an endopeptidase activated prodrug compared with free Dox has been demonstrated in a number of different tumour models including breast, colon, prostate and lung cancers. Pharmacokinetic and tissue distribution studies in normal and tumour-bearing mice have confirmed that an improved therapeutic index of the prodrug results in a tumour-selective release of Dox and a significant decrease in Dox levels in all normal tissues.
1. Introduction Doxorubicin (Dox) is among the most widely used cytotoxic agents for the treatment of various types of cancer, but the clinical benefit brought by this agent is limited due to its toxicity profile, which includes not only reversible acute adverse events such as myelosuppression, nausea, vomiting and alopecia but also irreversible cumulative cardiac damage [1]. Secondgeneration anthracyclines such as epirubicin showed some safety improvement, but the risk of inducing cardiomyopathy remains high [2]. During the last few decades, to improve the therapeutic index, a tremendous effort has been done to develop safer anthracyclines, focussing on analogues and tumour-targeted formulations [3]. DTS-201 (or CPI-0004Na), N-succinyl-b-alanyl-Lleucyl-L-alanyl-L-leucyl-Dox, is a peptidic prodrug of Dox that remains stable and inactive in its cellimpermeable prodrug form (Fig. 1). The drug has been developed by the late Trouet et al. [4]. In 2003, Diatos S.A. licensed from Medarex certain European rights to develop and commercialise DTS-201. Later Medarex (now a subsidiary of Bristol-Myers Squibb) granted full European commercialisation rights for DTS-201 to Diatos S.A.
O
OH
O
OH
O
HO HO
O
Na+
H N
O
H N
O N H
O
O
H N
O
O
O
N H
O
HO
Hemisuccinate N-masking group
β-Ala
Leu
Ala
Leu
Fig. 1. Chemical structure of DTS-201.
Doxorubicin
O
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Subsequent toxicology studies in rats showed that the chronic treatment with DTS-201 was less cardiotoxic when compared with free Dox at doses up to eight-fold higher. Increased tumour exposure with reduced cardiac exposure to Dox in animals after treatment with DTS201 provides a strong rationale for this prodrug approach [9]. Based on these interesting preclinical findings, DTS201 was selected as an investigational product for clinical development. The purpose of this first-in-man study was to assess the maximum tolerated dose (MTD), to characterise the safety profile, to determine the pharmacokinetic profile, to determine the phase II recommended dose (RD) and to assess the preliminary antitumour activity of DTS-201.
2. Materials and methods This phase I trial included adult patients with solid tumours whose disease had progressed on standard therapy, with a World Health Organisation performance status of 0 or 1, who had received a maximum of three lines of chemotherapy for locally advanced or metastatic disease, with absolute neutrophil and platelet counts 1500/mL and 100,000/mL respectively, normal serum albumin and creatinine, AST/ALT and alkaline phosphatase <2.5 of the upper limit of normal. Patients had normal cardiac function and a normal left ventricular ejection fraction (LVEF) at study entry. Exclusion criteria included prior anthracycline exposure of more than 300 mg/m2 of cumulative total equivalent of Dox or a failure of previous anthracycline-based chemotherapy within 6 months after adjuvant therapy or 3 months after discontinuation of treatment in the metastatic setting, serious concomitant illness, prior radiation therapy or systemic anticancer therapy within 4 weeks (6 weeks for mitomycin C and nitrosoureas), symptomatic brain metastasis and prior radiation therapy to more than 30% of the bone marrow. All patients gave written informed consent. This study had the approval of all responsible national and local ethics committees. The baseline evaluation was performed within 1 week before the study enrolment. Interim evaluation at each treatment cycle included physical examination, vital signs, electrocardiogram (ECG), concomitant medications and laboratory investigations. The tumour response evaluation was done every two cycles according to the Response Evaluation Criteria in Solid Tumours (RECIST) [10]. Laboratory investigations were done on days 8 and 15 of every treatment cycle. Cardiac monitoring was performed for every cycle using an ECG and serum troponin evaluations and through echocardiography for every other treatment cycle. Adverse events were monitored continuously throughout the study period and graded according to
the NCI-CTC criteria (version 3). For the determination of plasma levels of DTS-201 and analytes, blood samples were collected up to 72 h after the first administration of DTS-201. 2.1. Drug administration DTS-201 was supplied as a sterile red-orange lyophilised prodrug manufactured in compliance with Good Manufacturing Practice. It was supplied in 10-ml vials containing 100 mg of DTS-201 and 100 mg of lactose monohydrate. DTS-201 was reconstituted by adding sterile 5% D-glucose and administered as a 1-hour infusion. All doses of DTS-201 mentioned in this study report describe the Dox-equivalent dose. Standard prophylactic systemic anti-emetic treatment was allowed according to the protocol of each institution. 2.2. Study design The aim of this non-randomised, open-label, doseescalating, multicentre trial was to assess the MTD of DTS-201 administered as a 1-hour intravenous infusion every 3 weeks. Assessing safety, determining the RD and investigating clinical efficacy were the main secondary end-points. The dose escalation scheme was based on a modified Fibonacci schedule. Three patients entered at each dose level (DL), which could be extended to a maximum of 6 in case of dose-limiting toxicity (DLT). If two DLTs were observed at a given DL, the dose was declared the MTD, and no further dose escalation occurred. The MTD was determined according to the DLTs occurring during the first treatment cycle (3 weeks). The phase II RD was defined to be either the MTD or an intermediate DL between the MTD and the DL below. Patients continued treatment until disease progression or the occurrence of unacceptable toxicity or until at least six treatment cycles were completed. Treatment beyond six treatment cycles had to be discussed between the investigator and the sponsor on a case-by-case basis [11]. 2.3. Blood sampling and pharmacokinetic analysis According to protocol, 14 blood samples were drawn from all patients during the first cycle; at pre-dosing and then after the DTS-201 administration, at 15 and 30 min, 1, 1.5, 2, 3, 4, 6, 8, 24, 48 and 72 h. At each time point, 4 ml of venous blood was collected in polypropylene tubes containing citrate. The blood sample was then placed on ice and centrifuged for 10 min at 4 C. The plasma was transferred into two appropriate polypropylene tubes and was immediately frozen at 20 C. The pharmacokinetic analysis of the plasma levels of DTS-201 and its metabolites (AL-Dox, L-Dox, Dox and doxorubicinol) was performed for each patient
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at each DL using the trapezoidal method, the log-linear model (regression and the optimisation method).
3. Results Between July 2005 and June 2007, a total of 25 patients were enrolled into the study in three sites (one in Belgium and two in France). Thirteen patients were female and 12 were male. The mean age was 57.4 years (range, 30e71). Six patients had lung cancer and five had prostate cancer. Breast cancer, pancreatic cancer and head and neck cancer were the primary tumour for three patients each, two patients had soft-tissue sarcoma, the other patients had gastric, renal and oesophageal cancer. Patient characteristics are presented in Table 1. All patients were eligible for the trial. A total of 23 patients (92%) had visceral disease involvement. The mean number of disease sites was three per patient. The majority of patients had received surgery (68%), prior radiation therapy (72%) and prior chemotherapy (96%). Fourteen patients had received two prior lines of chemotherapy and six patients had received previous anthracycline treatment.
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201 administered reached 2750 mg/m2 in individual patients. The dose escalation schema is shown in Table 2. No DLTs were observed during the DLT window at the DLs of 80 and 160 mg/m2. DLTs occurred in one patient at the 250 mg/m2 DL (grade III mucositis) and in two patients in the 400 mg/m2 cohort (grade IV neutropenia lasting more than 5 days and grade III vomiting). The DLTs observed at this DL defined 400 mg/m2 every 3 weeks as the MTD and the phase II RD. To gain further insight into the safety and pharmacokinetics with this DL, six additional patients were treated at this dose, expanding the patient number to 12. One of the six additional patients developed a DLT (febrile neutropenia). 3.2. Deaths Four patients died within 30 days after study discontinuation, three due to disease progression (one at 160 mg/m2 and two at the 400 mg/m2 DL) after two cycles of treatment; the 4th patient died at the 160 mg/ m2 DL without signs of progression. There was no DTS201-related death.
3.1. MTD
3.3. Haematological toxicity
A total of 86 cycles of DTS-201 were administered to 25 patients (median two per patient; range, 1e8). Five cycles were given at the DL 80 mg/m2, 10 cycles at 160 mg/ m2, 24 cycles at 250 mg/m2 and 44 cycles at the 400 mg/ m2 DL. The maximum cumulative total dose of DTS-
Haematological toxicity was evaluated weekly with a complete blood count. Grade III or IV haematological toxicity was observed at the 400 mg/m2 DL, including neutropenia occurring in 11 of the 14 patients (91.7%). Grade III anaemia and thrombocytopenia occurred in five and one patient, respectively (Table 3). The median time to nadir of grade III or IV neutropenia was 15 days, with a relatively short median duration of 5 days.
Table 1 Patient characteristics. Characteristics
n (%)
Total number Age, years Median Range Gender Male Female Primary diagnosis Prostate cancer Breast cancer Pleural mesothelioma Pancreatic adenocarcinoma Non-small cell lung carcinoma Other Number of lines of prior chemotherapy 0 1 2 3 Prior radiotherapy Yes No Prior administration of anthracyclines
25 (100)
Table 2 Treatment dose levels.
59 30e71 13 (52) 12 (48) 5 3 3 3 2 9
(20) (12) (12) (12) (8) (36)
1 (4) 9 (37.5) 14 (58.3) 1 (4) 18 (72) 7 (28) 6 (24)
Treatment dose levels Dose level
DTS-201, mg/m2
DTS-201, mg doxorubicin equivalent/m2
Number of patients
DL1 DL2 DL3 DL4
80 160 250 400
45 90 140 225
3 3 7 12
Table 3 Haematological toxicity (number of patients by dose-level cohort). NCI-CTC grade IIIeIV
80 mg/m2 160 mg/m2 250 mg/m2 400 mg/m2 (3) (3) (7) (12)
Leukopenia Neutropenia Anaemia Thrombocytopenia Febrile neutropenia
0 0 0 0 1 (33.3%) 1 (33.3%) 0 0 0 0
0 0 0 0 0
10 (83.3%) 11 (91.7%) 3 (25%) 1 (8.3) 3 (25%)
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Neutropenia was complicated by fever in three patients and was observed at the MTD. A treatment delay for toxicity was necessary in only two patients, one for grade IV neutropenia after the first cycle and the second for grade III mucositis after the third course. Both were noticed at the 400 mg/m2 DL and led to a treatment delay of only 1 week. 3.4. Non-haematological toxicity All patients experienced at least one non-haematological adverse event. Table 4 summarises the drug-related adverse events. The number of patients with DTS-201related adverse events increased with increasing dose; however, the majority of side-effects were of mild to moderate intensity. The most commonly reported events were nausea, vomiting, fatigue and alopecia. No grade IV non-haematological toxicity occurred during the study. Grade III diarrhoea was observed in one patient at the 250 mg/m2 DL; another patient who received 250 mg/m2 of DTS-201 and who had a head and neck cancer previously treated with radiation therapy, developed grade III mucositis, which was interpreted as a recall radiation effect. This patient was replaced. Grade III nausea, vomiting, mucositis and asthenia were reported for one patient each in the 400 mg/m2 cohort. 3.5. Cardiac toxicity The majority of patients had normal ECG evaluations throughout the study. Three patients at the 400 mg/m2 dose had clinically asymptomatic ECG changes. One patient showed no significant abnormality during the treatment courses but a non-specific ST and T wave abnormality after six cycles of DTS-201. Another patient with cardiovascular risk factors (hypertension, hypercholesterolaemia and obesity) had an incidental increase of troponin after the sixth cycle, which was rapidly reversible and was considered as possibly drug related. No clinical cardiac symptoms have been reported for this patient; however, after the 7th cycle of DTS-201, the ECG showed a significant abnormality suggestive of myocardial ischaemia, but LVEF values remained unchanged during the whole study period. One patient had ECG findings consistent with myocardial infarction at study entry, but during the study, this Table 4 Grade III/IV non-haematological toxicity (number of patients by doselevel cohort). NCI-CTC grade III
80 mg/m2 (3)
160 mg/m2 (3)
250 mg/m2 (7)
400 mg/m2 (12)
Nausea Vomiting Mucositis Asthenia Diarrhoea
0 0 0 0 0
0 0 0 0 0
0 0 0 0 1 (14.3%)
1 1 2 1 0
(8.3%) (8.3%) (16.7%) (8.3%)
patient did not have any change in LVEF or ECG changes. LVEF values were comparable between dosing cohorts. No drop in LVEF was observed during the study period for the total patient population. 3.6. Tumour response Efficacy of DTS-201 was not the primary end-point for this phase I study, but 22 patients who received at least two cycles of treatment were evaluable for response according to RECIST. No partial or complete responses were observed at the 80, 160 and 250 mg/m2 DLs. In the 400 mg/m2 cohort, one patient with lung metastases from soft-tissue sarcoma, previously untreated with chemotherapy, achieved a confirmed partial response. In addition, 12 patients at different DLs achieved stable disease as the best RECIST response. 3.7. Pharmacokinetics and pharmacodynamics Fourteen blood samples were collected per patient at cycle 1, from the initiation of infusion and up to 72 h post dose. Pharmacokinetic analysis demonstrated that DTS-201 is metabolised to AL-Dox, L-Dox and then to Dox and doxorubicinol. DTS-201 concentration peaked at the end of the 1-hour infusion and then declined rapidly. The metabolites followed distinct patterns: ALDox was barely detectable in most samples; L-Dox followed a time course parallel to that of DTS-201 with a Cmax also reached at the end of the infusion; Dox and doxorubicinol appeared later (Tmax of 1.25 and 4 h, respectively) and were present in plasma for longer periods than DTS-201. The plasma concentration versus time curves of DTS-201 and its metabolites generated with the results obtained from the 12 patients treated at 400 mg/m2 are presented in Fig. 2. Area under the curve (AUC) values of DTS-201 and its metabolites are presented in Table 5. For the parent drug as for metabolites, the AUC0-T was linearly correlated with the dose. L-Dox, Dox and doxorubicinol had AUC values 4- to 12-fold lower than those of DTS-201. AL-Dox seemed to be a minor metabolite with AUC values 250- to 1000fold lower than those of DTS-201. The proportions of the various metabolites were independent of the administered dose of DTS-201. The main pharmacokinetic parameters of DTS-201 (total plasma clearance, elimination half-life and total volume of distribution at steady state) were also independent of the DL administered. Of note, plasma AUCs of Dox after administration of 400 mg/m2 DTS-201 were similar to those obtained after administration of a dose of 50e60 mg/m2 of conventional Dox, whereas Cmax values were much lower, and the doxorubicinol/Dox ratio was higher. These features are important when considering the dose equivalence for haematologic and cardiac toxicity. We also observed a significant relationship between
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Pla sm a co ncentratio n (ng/m L
100000
A
10000 1000 100 10 1 0
Pla sm a co ncentra tion (ng /m L
10000
2
B
4 Time (hours) 1000
6
8
C
1000 100 100 10 10
1
1 0
2
4 Time (hours)
6
8
0
20
40 Time (hours)
60
80
Fig. 2. Plasma concentration versus time curves of DTS-201 and its metabolites. Data collected from 12 patients treated at the dose 400 mg/m2. Values are mean SD. DTS-201 (- -), AL-Dox (ο), L-Dox ( × ), doxorubicin (- -), doxorubicinol (◊). (A) DTS-201 concentration evolution. (B) Metabolites pharmacokinetics profile up to 8 h post dose. (C) Doxorubicin and doxorubicinol concentration up to 72 h post dose.
leucocyte counts and Dox AUC (and not the prodrug AUC). Table 6 summarises the key pharmacokinetic parameters of DTS-201. 4. Discussion Conventional anthracyclines are widely used cytotoxic agents for the treatment of multiple types of cancer; however, the clinical benefit with these agents is limited due to their safety profile, in particular the well-known cardiotoxicity. The overall risk of conventional anthracycline-induced cardiotoxicity is related to the cumulative administered dose of the agents. Conventional Dox-induced congestive heart failure may occur at cumulative doses lower than the currently accepted lifetime cumulative dose of 450e500 mg/m2, especially in older patients. The incidence of heart failure was Table 5 AUC values (ng/ml h) of DTS-201 and its metabolites. Number of patients at each dose level indicated between parentheses. Results are given as mean values (SD for the 400 mg/m2 data). 80 mg/m2 (3) 160 mg/m2 (3) 250 mg/m2 (7) 400 mg/m2 (12) DTS-201 AL-Dox L-Dox Dox Dox-ol
1364 3.33 125 101 222
4476 4.26 577 390 867
6118 20.9 1027 853 1308
11,062 4459 29.3 11.4 1389 385 1418 378 2348 1030
reported to be 2%, 8% and 26% of patients at total cumulative doses of 300 mg/m2, 450 mg/m2 and 550 mg/ m2, respectively [12]. During the last 30 years, research has focussed to develop more-effective and less-toxic anthracyclines. The initial attempt concentrated on analogues of Dox and daunorubicin, without achieving a significant improvement in the therapeutic index. Other alternatives included the use of long infusion schedules, Table 6 Pharmacokinetic parameters of DTS-201. 80 mg/m2 160 mg/m2 250 mg/m2 400 mg/m2 (1) (3) (7) (12) Total plasma clearance (L/h) Elimination half-life (h) Volume of distribution (L) Mean residence time (h)
71.3
65.9
90.8
86.0 31.0
0.112
0.303
0.425
0.385 0.347
11.5
12.0
19.5
27.4 12.2
0.161
0.198
0.234
0.322 0.116
The pharmacokinetic parameters of DTS-201 were estimated with the APIS software, using a model at 1 or 2 compartments, chosen according to the Akaike criterion. The parameters were independent from the dose administered. The data best fitted a one-compartment model for 15 patients and a two-compartment model for 8 patients. In two cases, at the dose of 80 mg/m2, no modelling was possible. The use of two or three compartments did not impact on total plasma clearance, volume of distribution at steady state or mean residence time but impacted on the half-life, the use of two compartments giving rise to apparently longer elimination half-lives.
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of iron-chelating agent dexrazoxane and ACEinhibitors, and the development of tumour-targeted formulations, including liposomal or albumin-bound anthracyclines or the conjugation of anthracyclines to a carrier that specifically recognises tumour cells. DTS201 is a Dox prodrug that is unable to enter normal cells but is activated by peptidases secreted by cancer cells. In preclinical models, DTS-201 was found to be more effective and less cardiotoxic than free Dox. In the present study, we have shown that DTS-201 can be administered safely at doses of Dox higher than those usually prescribed. To reach the MTD, the Doxequivalent dose can be increased by a factor of 3: 400 mg/m2 of DTS-201 corresponds to 225 mg/m2 of free Dox, which is three times higher than the standard 75 mg/m2 of conventional Dox used as a single agent in many diseases. At this high DL, the acute toxicity profile of DTS-201 was similar to that of Dox, including myelosuppression, mucositis, nausea, vomiting and alopecia in the absence of cardiac toxicity. Interestingly, the neutropenic episodes in this study were of very short duration and fully reversible. Five patients in the MTD cohort received a total of six cycles of therapy, reaching a total cumulative dose of 2750 mg/m2, which corresponds to a dose of 1546 mg/m2 of free Dox. This cumulative dose of Dox is about threefold higher than the generally recommended cumulative lifetime dose of the conventional cytotoxic agent. Cardiac safety was closely monitored throughout our study. All patients had longitudinal ECG, plasma troponin and cardiac ultrasound assessments. No significant drop in LVEF was noticed. One patient with a history of cardiovascular risk factors had an incidental increase of troponin after the sixth cycle. This was rapidly reversible, not complicated by clinical cardiac findings but was considered as possibly drug related. Of note, incidental increases in serum troponin are not an uncommon finding in patients with advanced solid tumours. Plasma concentrations of DTS-201 increased linearly with increasing dose. The pharmacokinetic profile of DTS-201 is characterised by a relatively short half-life and a small volume of distribution, indicating that DTS201 remains in the plasma compartment and is progressively converted into AL-Dox and L-Dox and then to Dox by further enzymatic cleavage. The Dox AUC after treatment with DTS-201 at 400 mg/m2 is within the range of AUC values reported for 50e60 mg/m2 of free Dox [13e16]. Despite that the objectives of this study were to determine the MTD and the phase II RD, 59% of the patients entering this trial had clinical benefit: one patient had a confirmed partial response and 12 patients achieved disease stabilisation. Disease control was observed in different tumour types. On the basis of the phase I trial presented here, Diatos S.A. started two phase II trials, one in advanced prostate adenocarcinoma and one in metastatic breast cancer.
In summary, this first-in-man study validated the concept that an extracellularly tumour-activated anthracycline prodrug can be used safely in patients with advanced malignancies and that the administration of such agent is associated with an improved therapeutic window. The toxicity profile after administration of higher doses of DTS-201 appeared less severe than that observed with the administration of standard doses of free Dox. During dose escalation, patients could be safely exposed to repeated cycles of DTS-201 with doses up to three-fold higher than the recommended cumulative lifetime maximum dose of conventional Dox. Moreover, no severe acute cardiac toxicity was observed in this trial. Some signs of tumour activity in various tumour types were seen, which is encouraging but needs to be confirmed in clinical phase II studies. Future studies will also have to assess long-term safety of this tumour-activated anthracycline prodrug, as cardiac toxicity due to conventional Dox can also occur after longer treatment-free intervals. In addition, the role of the endopeptidases as potential predictive biomarkers for the antitumour effects of the prodrug should be assessed. We also hypothesise that this agent might be active in solid tumours beyond the traditional Dox-sensitive entities, due to a specific high activity of peptidases found in some cancers. These enzymes would then be responsible for an indirect ‘vectorisation’ or delivery of very high concentrations of the active compound in the vicinity of tumour cells. Partly sparing the cardiac exposure to toxic metabolites, we also believe that this drug could allow both prolonged and repeated anthracycline exposure of patients with Dox-sensitive tumours. This is supported by DTS-201 cardiac safety profile as observed in this phase I study. Further development of DTS-201 should focus on patients with and without prior anthracycline exposure. Patients could potentially be selected for such treatment by the presence or absence of the endopeptidases required for cleavage of the agent. Based on the safety profile of the drug, DTS-201 would also qualify as a combination partner with other cardiotoxic or noncardiotoxic anticancer agents [17]. The working hypothesis behind the development of DTS-201 has been developed further in sarcoma. A DTS-201-related endopeptidase-activated prodrug, ALGP-Dox, has recently been tested in patient-derived xenograft sarcoma models. ALGP-Dox caused tumour volume stabilisation in de-differentiated liposarcoma xenografts and significant tumour shrinkage in synovial sarcoma, continuing after treatment cessation. A significant decrease in proliferation and an increase in apoptosis compared with control and Dox was observed during and after treatment in all tested models. ALGPDox showed higher antitumoural efficacy compared with Dox and the administration of a 30- to 40-fold higher dose of ALGP-Dox was tolerated without significant adverse events [18].
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In the clinic there remains a high need for further optimisation of anthracycline treatment, both in solid tumours and in haematological malignancies, illustrated by the presentation of randomised phase III data exploring the albumin-bound drug aldoxorubicin in patients with advanced soft-tissue sarcoma, but also by the very recent approval of a liposome-encapsulated combination of daunorubicin and cytarabine for the treatment of adults with newly diagnosed, therapyrelated acute myeloid leukaemia or leukaemia with myelodysplasia-related changes [19,20].
[6]
[7]
[8]
[9]
Conflict of interest statement [10]
Jamal Gasmi is a former employee of Diatos S.A. and approved the submission of this manuscript. The remaining authors declare no conflicts of interest. [11]
Acknowledgements [12]
The authors want to dedicate this article to the late Prof. Andre´ Trouet, who developed DTS-201 and related compounds but passed away on 03-04-2014. We also want to thank Denis Ravel, Florence Gonzalez, Maria Quedraogo, Vincent Dubois, John Tche´linge´rian, Elise Assouly, Karine Vialatte and Matthieu Michel for their support and suggestions during the study. We also thank Azzeddine Cherfi for his advice regarding biometrics.
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